Some vendors and some listing sites show at least two exchange rates. National currency and the cryptocurrency of choice. Stripe and Coinbase give the options

Some vendors and some listing sites show at least two exchange rates. National currency and the cryptocurrency of choice. Stripe and Coinbase give the options of automatic conversion to the cryptocurrency exchange rate when displaying it. Some merchants, usually more established ones like Microsoft, Newegg, Namecheap, typically won't show the bitcoin price until you chose that option and they generate the timed invoice.